1. Field of the Invention
The present invention relates to a cutting device such as a portable circular saw, and particularly to a cutting device that cuts a workpiece such as wood by rotating a circular cutting blade (saw blade).
2. Description of the Related Art
A cutting device such as a portable circular saw may have a cutting device main body in which a circular cutting blade rotates via the driving of an electric motor. The cutting device main body is disposed at an upper side of a base. The base is brought into contact with an upper surface of a workpiece. A user can cut a workpiece by moving the cutting device in a cutting direction. The cutting blade protrudes toward a lower surface side of the base cuts into the workpiece.
In these kinds of cutting devices, various improvements have been made to effectively process cutting powder generated by the cutting of a material and increase the efficiency of the cutting. In particular, a marking line guide for positioning a cutting blade on a marking line drawn on the workpiece is provided on a front end side of the base. In case that the marking line guide and the marking line are not easily viewed due to accumulation of the cutting powder, rapid cutting cannot be performed. Considering this situation, improvements have been made to appropriately process the cutting powder in the vicinity of the marking line guide.
For example, Japanese Laid-Open Patent Publication No. 2005-193572 discloses that cutting powder is prevented from being accumulated by purging the power accumulated around the marking line guide (top guide) provided on a front side of a base by using cooling air that is discharged from an electric motor. Further, Japanese Laid-Open Patent Publication No. 2006-088559 discloses that cutting powder is prevented from being accumulated on a base by effectively collecting the cutting powder in a collection path provided in a blade case using a flow generated by the rotation of a cutting blade and a cooling air from an electric motor. In addition, Japanese Laid-Open Patent Publication No. 2009-214292 discloses a technique that prevents cutting powder from being accumulated by effectively introducing cooling air exhausted from a cutting device main body into a front portion of a base.
In a cutting device such as a portable circular saw, the cutting powder may accumulate largely in the vicinity of the marking line guide provided on the front side of the base. This thereby reduces the visibility of the marking line guide. In order to prevent a reduction in the operability of the cutting device, improvements have been made such that the cutting powder is prevented from being accumulated in the vicinity of the marking line guide of the base front end by purging the power with cooling air discharged form the cutting device main body.
However, in these kinds of cutting devices, a cutting device main body is configured to incline on a right side or left side in a cutting direction with respect to a base to perform so-called an inclination cutting. Further, it is configured such that in order to purge cutting power accumulated around a marking line guide on a front side of a base with a cooling air, a ventilation pipe portion is provided on a rear side of a blade case to guide the cooling air discharged from an exhaust port of an electric motor to the front side of the base. Accordingly, when the cutting device main body is inclined with respect to the base to perform the inclination cutting, a purging direction of the cooling air discharged from the ventilation pipe portion is changed and sufficient air is not applied to the vicinity of the front side of the base. As a result, purging of the cutting powder is not sufficiently performed and the ease in operation of the tool can deteriorate.
Thus, there is a need to maintain high operability by effectively purging the cutting power with the cooling air exhausted from the cutting device main body to the vicinity of a top guide of the front side of the base. This needs to be maintained when the cutting device main body is positioned not only at a perpendicular cutting position but also at an inclination cutting position.